(a) Field of the Invention
The present invention relates to a fuel cell system, and, more particularly, to a fuel cell system having a reformer.
(b) Description of the Related Art
A fuel cell system is an electricity generating system which directly converts chemical reaction energy of oxygen and hydrogen contained in a hydrocarbon material, such as methanol, ethanol, natural gas, etc., into electrical energy.
A polymer electrolyte membrane fuel cell (PEMFC) has been recently developed to have an excellent output characteristic, a low operating temperature, and fast starting and response characteristics. In addition, the PEMFC advantageously has a wide range of applications including a mobile power source for vehicles, a distributed power source for home or other buildings, and a small-size power source for electronic apparatuses.
A fuel cell system employing the PEMFC includes a stack, a reformer, a fuel tank, and a fuel pump. The stack constitutes an electricity generation assembly constructed with a plurality of unit cells, which generate electrical energy through a reaction of hydrogen and oxygen, and the fuel pump supplies the fuel of the fuel tank to the reformer. The reformer then absorbs thermal energy supplied by a burner, reforms the fuel through a catalytic reaction to generate a reforming gas containing hydrogen, and supplies the reforming gas to the stack.
However, in the fuel cell system employing the PEMFC, the fuel pump must operate in order to supply the fuel to the reformer. The power consumed for the operation becomes a parasitic power which needs to be generated in addition to a power for driving the whole fuel cell system. Therefore, there is a problem in that the parasitic power causes a decrease in performance and energy efficiency of the entire fuel cell system.
In addition, since the conventional fuel cell system requires a space for the fuel pump, there is a problem in that it is impossible to implement a compact fuel cell system.
In addition, in the conventional fuel cell system, since a fuel supplied to the reformer is preheated by a preheating unit, there is a problem in that the power consumption of the preheating causes a further deterioration in the performance of the entire fuel cell system.